The present disclosure relates to the detection of subsurface objects and/or structures, and more particularly to detecting and imaging of deep structures of high electrical impedance contrast compared to their subsurface environments.
Current methods for identification of high impedance contrast objects, and in particular, voids, and tunnels are based on Ground Penetrating Radar (GPR), which utilizes active electromagnetic sources. Controlled, active sources are local and decay rapidly. Therefore, GPR has limited penetration depth. Other methods include statistical sample drills, which can be expensive and limited in terms of spatial resolution, and seismic optic fibers, that cannot detect preexisting subsurface structure and are highly sensitive to background noise.